Infusion pumps, drug pumps and medication delivery devices are well-known and widely used throughout the world today. Intravenous infusion pumps were developed decades ago to pump fluid medicants or nutrients through a tube set to a patient in connection with treatment of a medical condition. Infusion pumps include peristaltic pumps, roller pumps, or expulsor pumps, for example. Various pumps include a reusable control module that is detachably coupled to a pressure plate on the top of a disposable or reusable fluid reservoir cassette. Fluid is pumped from the cassette by the reusable control module when the cassette is coupled to the control module. Alternatively, other variations of infusion pumps include a reusable pump control module and pressure plate cassette as part of an administration set that is used in conjunction with a remote IV bag or fluid reservoir which is separate from the pump control.
Infusion pumps operate by governing the movement of fluid through a delivery tube by selectively occluding portions of the tube by depressing a valve or mechanism against the tube. For example, in some pumps the mechanism of a pump selectively engages the tube against the pressure plate in a peristaltic fashion to force fluid through the tube.
In the past, one potentially problematic situation has been identified which is referred to as “free-flow”. Free flow occurs in infusion pumps when fluid flows freely from the source of fluid through the tube into the patient. Medical personnel and pump operators try to avoid the occurrence of free-flow when administering fluids to patients.
Free-flow may cause serious harm to a patient due to overmedication. Accordingly, designs and devices have been developed to prevent free flow in infusion pumps. Although many of the free-flow prevention designs are somewhat effective, many designs suffer from arrangements that are difficult to manufacture or assemble. For example, many current pressure plate arrangements for delivery tube placement contain features which pose hard to assemble designs. Further, the components and operation of past pressure plate designs are believed to be less than optimal and leave considerable room for improvement.
Therefore, improved methods and apparatus for selectively restricting fluid flow of an infusion pump are desired, including improvements to the pressure plate.